What Is Metformin? Side Effects, Dosage, and Risks

By Craig Sorkin, DNP, APN
Medically reviewed checkmarkMedically reviewed
February 24, 2023

Metformin is a prescription medication typically taken by people with type 2 diabetes to help manage blood sugar. However, metformin may benefit more than just glucose. Studies show people who take metformin may also experience weight loss.

Read on to learn more about Metformin, including its uses, side effects, interactions, and more.

What is Metformin?

Metformin (brand name: Glucophage) is available by prescription only. Healthcare providers prescribe this medication to help treat type 2 diabetes. When paired with a doctor-approved diet, metformin helps better control blood sugar in those with type 2 diabetes.

Metformin comes in a tablet or oral solution. The generic version offers an immediate-release form, while the brand name Glucophage offers an extended-release form. Your medical provider will prescribe the appropriate form of metformin for you.


Metformin is FDA-approved for type 2 diabetes. When a person receives a type 2 diabetes diagnosis, their health professional will encourage lifestyle changes such as diet and exercise to improve the condition. If diet and exercise fail to improve blood sugar, your provider may prescribe metformin as a first-line medication to help keep blood sugar in a healthy range. 

Metformin also has several non-FDA-approved indications, such as treating:

  • Gestational diabetes
  • Prediabetes 
  • Polycystic ovary syndrome (PCOS)
  • Antipsychotic-induced weight gain

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How it Works

Metformin reduces blood sugar levels in the following ways:

  • Reduces the amount of glucose the liver makes
  • Increases insulin sensitivity
  • Decreases the amount of sugar the intestines absorb

The medication usually does not cause low blood sugar (hypoglycemia) when taken as directed. It begins to work approximately three hours after taking it. Always follow your healthcare provider’s instructions when taking metformin, as taking the medication at the wrong time or in the wrong form can interfere with its effectiveness or cause additional side effects.


Over the years, metformin has consistently demonstrated its effectiveness in managing type 2 diabetes. Trials have also shown a 31%-58% decrease in diabetes progression with intensive lifestyle changes paired with metformin, according to research published in Diabetes Spectrum. These results suggest metformin is an effective medication to help control type 2 diabetes.

Metformin Cost

Metformin costs vary based on several factors, such as whether you have insurance and the pharmacy you use. Read on to learn more about the cost of metformin with and without insurance.

With Insurance

The cost of metformin with insurance can vary widely. Your insurance provider, the dosage you need, and your local pharmacy price all play a role in determining how much you’ll pay. If you’re taking the generic version, you may pay nothing. However, the brand-name version may cost much more—even with insurance.

Depending on your insurance plan, you may have a specific co-pay. A co-pay is a fixed fee you pay when you fill your prescription. Be sure to check with your insurance company, healthcare provider, and pharmacist to ensure you are getting the best price.

Without Insurance

Depending on your pharmacy, the cash price for 500 mg metformin tablets is usually around $13-$22 for 100 tablets. The cost may be much more if you purchase the brand version of metformin. 

Read K Health’s Guide on Metformin Costs

Ways to Save Money

A discount drug coupon is one of the best ways to save money on metformin. These coupons are available through most pharmacies, and you can use them for both brand-name and generic medications. Look for discount drug coupons online or at your local pharmacy.

You may qualify for a patient assistance program. These programs provide prescription medications to people who cannot afford them otherwise. Your doctor or pharmacist can help determine if you’re eligible and how to apply. You can also contact the medication manufacturer to learn about its available programs.

Finally, consider ordering a 90-day supply of your medication. Most pharmacies offer a discount when you buy a larger quantity. Check with your pharmacist for information on 90-day supplies. 

Metformin for Weight Loss

While metformin has a long history of treating type 2 diabetes, recent studies suggest metformin may help people lose weight. In a 2020 study, participants lost more weight over 29 weeks than those who took the placebo. Unlike other medications for diabetes, metformin can help reduce excessive weight gain when taken along with diet and exercise. 

It’s important to note that the FDA has not approved metformin as a weight loss medication. Because of that, healthcare professionals will not prescribe metformin for the sole purpose of weight loss. However, if you have type 2 diabetes and need metformin for blood sugar control, you may benefit from its weight management effects.


Because metformin is not a weight loss medication, there is no specific dose for weight loss. People with type 2 diabetes typically start taking metformin 500 mg twice daily. If this dose doesn’t help control blood sugar, your health provider may increase the dose to a maximum of 2550 mg daily. 

Side Effects

The most common side effects of metformin include:

  • Low blood sugar
  • Upset stomach or vomiting
  • Diarrhea

Less common may include:

  • Muscle pain or weakness
  • Feeling cold
  • Trouble breathing
  • Feeling dizzy or light-headed
  • Stomach pain or vomiting
  • Irregular or slow heart rate

If you have any of the above symptoms, you may be experiencing a condition called lactic acidosis which is a medical emergency. Seek emergency medical care or call 911. 

Symptoms of an allergy to metformin include hives, trouble breathing, and swelling of your lips, tongue, or throat. Call 911 if you have an allergy to metformin. 

Read K Health’s Guide on Side Effects and Risks of Metformin

Metformin Alternatives

Other medications are also available to treat type 2 diabetes. Some people are prescribed insulin injections. Insulin is a hormone produced by the pancreas that helps regulate blood sugar levels.

Other medications are also available, such as GLP-1 agonists. These medications help manage blood sugar for people with type 2 diabetes and may also help you lose weight. Several other oral medications can also help control the condition. Talk with your healthcare provider about the best options for you.

How to Take Metformin

Follow your medical provider and pharmacist’s instructions for taking metformin. Typically, metformin is taken with a meal—unless otherwise indicated by your provider. Never crush or chew an extended-release pill. The oral solution should be shaken and measured carefully.


Several drugs can interact with metformin. Two common medications with a strong interaction with metformin are Lantus and Synthroid. Taking them both may increase metformin’s effect on your blood sugar or increase your risk for lactic acidosis. Be sure to discuss all your medications, supplements, and vitamins with your medical provider before taking metformin. 

Drinking alcohol while taking metformin should also be avoided. A small amount of alcohol on occasion is generally safe. However, consuming large amounts of alcohol increases your risk of lactic acidosis and low blood sugar.

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Contraindications and Precautions

Do not take metformin if you have metabolic acidosis, severe kidney disease, or diabetic ketoacidosis. If you ever need medical imaging, such as an x-ray or CT scan that requires a dye injection into your veins, you may need to stop taking metformin temporarily. Discuss this with the provider ordering and administering the imaging test.

You should also speak with your provider if you plan to become pregnant or are breastfeeding while taking metformin.

Metformin can sometimes cause a person’s blood sugar to drop too low, a condition called hypoglycemia. Symptoms of hypoglycemia include:

  • Weakness
  • Confusion
  • Feeling shaky or weak
  • Headache
  • Drowsiness
  • Dizziness
  • Hunger
  • Clammy skin
  • Irritability
  • Fast heartbeat

Knowing the signs of low blood sugar and the correct treatment is crucial. Your doctor may prescribe a medication called glucagon to counteract hypoglycemia. Also, educate your friends and loved ones about hypoglycemia so they can help you when needed. To avoid getting hypoglycemia, always remember to eat when you take your metformin. Eating frequent small meals is often preferred over three larger meals.

How K Health Can Help

Now you can manage diabetes from home using K Health. Get metformin online in three easy steps:

  1. Answer a few simple questions.
  2. Meet your primary care provider.
  3. Get the prescription/ care you need.

Frequently Asked Questions

How quickly can you lose weight on metformin?
While studies suggest people may lose weight on metformin, the research focused on weight loss over more extended periods. There is no factual data on how quickly a person loses weight while taking metformin. Weight loss also depends on your lifestyle and diet patterns.
How much weight can you lose in a month on metformin?
No data exists on how much weight you can lose in one month on metformin. Metformin is not intended for rapid weight loss. However, research suggests those taking metformin while following a diet and exercise routine tend to lose weight.
How can I speed up weight loss with metformin?
To maximize any weight loss effects of metformin, follow your medical provider's instructions on taking metformin correctly. Also, discuss what diet you should follow and how much exercise is appropriate while taking metformin.
What’s the average weight loss on metformin?
Participants in one study lost an average of 8.3 lbs over 29 weeks of taking metformin. These people were also following a restricted diet and getting regular physical activity.
What’s the dosage of metformin for weight loss without diabetes?
Metformin is not prescribed for weight loss purposes. Several off-label metformin uses include polycystic ovarian syndrome (PCOS) and prediabetes. The typical dosage of a person taking metformin for type 2 diabetes is 500 mg, taken twice daily with a meal.
How much does metformin cost without insurance?
The cost of metformin without insurance depends on your pharmacy and dose. The average price for 100 tablets of 500 mg metformin is between $13-$22.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Craig Sorkin, DNP, APN

Craig Sorkin, DNP, APN is a board certified Family Nurse Practitioner with over 15 years experience. He received his Undergraduate and Graduate degrees from William Paterson University and his doctoral degree from Drexel University. He has spent his career working in the Emergency Room and Primary Care. The last 6 years of his career have been dedicated to the field of digital medicine. He has created departments geared towards this specialized practice as well as written blogs and a book about the topic.

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